Q1 - Three-year-old Sara

[rdown2b]

I initially picked B but I can see why its D because its circular reasoning? Can someone explain the stimulus?

[giladedelman]

Thanks for posting!

It's not exactly circular reasoning. The premise is that Sara and Michael probably have the same illness. But then, from the additional premise that Michael doesn't have strep, the argument concludes that Sara definitely doesn't have strep. So we're going from a "probably" premise to a "definitely" conclusion, which is a no-no. That's why (D) is correct.

[xmomo]

Can someone please explain why the wrong answers are incorrect, particularly A and E?

Thank you.

[dl0120]

Can someone please explain why the wrong answers are incorrect, particularly A and E?

Thank you.

A says Premise = Conclusion. There's no premise that is the exact same as the conclusion

E is making a generalization from unrepresentative samples. It's a bit more convoluted b/c it says the examples are intended to represent RESPECTIVE groups. Applying it here would be something like if the argument assumed that Sara represents all 3 year old girls and Michael represents all 3 year old boys.

Applied argument, modified to accommodate E

Sara does not have strep infection
Michael has strep infection
---
Therefore, all 3 year old girls do not have strep infection
Therefore, all 3 year old boys have strep infection

Notice how this is so different from the original argument. That's because the argument does not exhibit this flaw.

[uhdang]

Pretty touch question for #1 in my opinion.
This is Flaw question.

Here is the Core:

Sara and Michael are both ill and show same symptoms. + They play together every afternoon ==>
Sara probably has the same illness as Michael does + Michael definitely does not have a streptococcal infection + He has one of the symptoms
==>
Illness that Sara has is definitely not a streptococcal infection either.

@ Premise and intermediate conclusion advocates that Sara and Michael probably have the same illness since they always play together. But here, there is “PROBABLY.” It is not 100% certain. And it goes on to say that since Michael "definitely" doesn't have streptococcal infection, Sara ALSO "definitely" doesn't have that disease. Michael might "definitely" not have that disease, but as far as we know, since we are given that they "probably" have the same disease, Sara might have something other than the same disease as Michael. Sara's case is NOT definite. This is Error in usage of Evidence where the author makes a factor (Sara and Michael "probably" have the same disease) that might contribute to strengthen the conclusion to make certain of the conclusion.

===== Here are answer choice analyses =====

A) Circular reasoning? None I can find.

B) Confusing the cause and effect? Not happening here. There are two sets of potential cause and effect (Playing together causing same illness & Michael doesn't have a SI causing Sarah not having SI), but no confusion of reversing them in either case.

C) We are not informed of any “less severe” disease. Out of scope.

D) This is what we have discussed above. Changing "probability" to "certainty" CORRECT

E) Mistakenly applying quality to each individual and group flaw? Nope. We are not given any group.